KR102580743B1 - Cathode active material, and lithium ion battery including the same - Google Patents

Abstract

These embodiments relate to a positive electrode active material and a lithium secondary battery containing the same. According to one embodiment, a positive electrode active material for a lithium secondary battery is provided, including metal oxide particles containing nickel, cobalt, and manganese, and five types of doping elements doped into the metal oxide particles.

Description

Cathode active material and lithium secondary battery containing the same {CATHODE ACTIVE MATERIAL, AND LITHIUM ION BATTERY INCLUDING THE SAME}

These embodiments relate to a positive electrode active material and a lithium secondary battery containing the same.

Recently, thanks to the explosive increase in demand for electric vehicles and the demand for increased driving range, the development of secondary batteries with high capacity and high energy density that can be applied to electric vehicles is actively underway around the world.

In particular, in order to manufacture such a high-capacity battery, a high-capacity positive electrode active material must be used. Accordingly, a method of applying a nickel-cobalt-manganese-based positive electrode active material with a high nickel content is being proposed as a high-capacity positive electrode active material.

However, as the nickel-cobalt-manganese-based positive active material has a high nickel content, as the nickel content increases, 1) efficiency decreases due to a decrease in capacity, 2) formation of a NiO rock salt structure phase and deterioration of cycle characteristics due to the generation of surface oxygen, and 3) resistance. Problems such as increase will appear.

Therefore, there is an urgent need to develop a positive electrode active material that can solve the problems of nickel-cobalt-manganese-based positive electrode active materials with high nickel content.

In this embodiment, by doping five types of elements into metal oxide particles containing nickel, cobalt, and manganese, the problem of performance degradation occurring in positive electrode active materials with a high nickel content can be solved and the electrochemical properties can be significantly improved. The object is to provide a positive electrode active material and a lithium secondary battery containing the same.

The cathode active material for a lithium secondary battery according to an embodiment may include metal oxide particles containing nickel, cobalt, and manganese, and five types of doping elements doped into the metal oxide particles.

The five types of doping elements may be Al, Nb, B, Zr, and Ti.

In this embodiment, the doping amount of Al may range from 0.006 mole to 0.029 mole based on 1 mole of the total of nickel, cobalt, manganese, and doping elements.

The doping amount of Nb may be in the range of 0.00025 mole to 0.005 mole based on 1 mole of the total of nickel, cobalt, manganese, and doping elements.

The doping amount of B may be in the range of 0.001 mole to 0.015 mole based on 1 mole of the total of nickel, cobalt, manganese, and doping elements.

The doping amount of Zr may range from 0.001 mole to 0.007 mole based on 1 mole of the total of nickel, cobalt, manganese, and doping elements.

The doping amount of Ti may range from 0.0002 mole to 0.0015 mole based on 1 mole of the total of nickel, cobalt, manganese, and doping elements.

The doping amounts of Nb, Al, and Zr may satisfy the relationship shown in Equation 1 below.

[Equation 1]

4 < ([Zr]+[Al])/[Nb] < 210

(In Equation 1, [Nb], [Al], and [Zr] mean the doping amount of each element based on 1 mole of nickel, cobalt, manganese, and the total of the doping elements)

The doping amounts of Nb, Ti, and B may satisfy the relationship in Equation 2 below.

[Equation 2]

3 < ([B]+[Ti])/[Nb] < 120

(In Equation 2, [Nb], [Ti] and [B] mean the doping amount of each element based on 1 mole of nickel, cobalt, manganese and the total of the doping elements)

The positive electrode active material may be represented by the following formula (1).

[Formula 1]

Li _a [Ni _x Co _y Mn _z ] _1-t (Al _h Nb _i Zr _j B _k Ti _m ) _t O _{2- p}

(In Formula 1 above,

X is one or more elements selected from the group containing F, N, and P,

a is 0.8 ≤ a ≤ 1.3,

t is 0.008 ≤ t ≤ 0.05,

0.6 ≤ x ≤ 0.95, 0 < y ≤ 0.2, 0 < z ≤ 0.2, 0.006 ≤ h ≤ 0.025, 0.00025 ≤ i ≤ 0.005, 0.001 ≤ j ≤ 0.007, 0.006 ≤ k ≤ 0.029, 0.0002 ≤ m ≤ 0.015, 0 ≤ p ≤ 0.02.)

The initial diffusion coefficient of the positive electrode active material may range from 6.91*10 ^-9 m ² /sec to 7.58*10 ^-9 m ² /sec.

The crystal grain size of the metal oxide particles may range from 1,036 Å to 1,440 Å.

The full width at half maximum (FWHM) value for the (110) plane of the metal oxide particle may range from 0.126 to 0.204.

When measuring an

The content of nickel in the metal oxide particles may be 0.8 mol or more, based on 1 mol of the total of nickel, cobalt, and manganese.

A lithium secondary battery according to another embodiment may include a positive electrode including a positive electrode active material according to an embodiment, a negative electrode, and a non-aqueous electrolyte.

When applied by doping at least five types of elements into NCM metal oxide particles, the positive electrode active material according to this embodiment increases the capacity of a lithium secondary battery while improving room temperature and high temperature lifespan characteristics, initial efficiency, initial resistance, resistance increase rate, and heat. Stability can be significantly improved.

Terms such as first, second, and third are used to describe, but are not limited to, various parts, components, regions, layers, and/or sections. These terms are used only to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, the first part, component, region, layer or section described below may be referred to as the second part, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is only intended to refer to specific embodiments and is not intended to limit the invention. As used herein, singular forms include plural forms unless phrases clearly indicate the contrary. As used in the specification, the meaning of "comprising" refers to specifying a particular characteristic, area, integer, step, operation, element and/or ingredient, and the presence or presence of another characteristic, area, integer, step, operation, element and/or ingredient. This does not exclude addition.

When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part or may be accompanied by another part in between. In contrast, when a part is said to be "directly on top" of another part, there is no intervening part between them.

Although not defined differently, all terms including technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted as having meanings consistent with related technical literature and currently disclosed content, and are not interpreted in ideal or very formal meanings unless defined.

The cathode active material for a lithium secondary battery according to one embodiment may include metal oxide particles including nickel, cobalt, and manganese, and five types of doping elements doped into the metal oxide particles.

At this time, the five types of doping elements may be Al, Nb, B, Zr, and Ti.

In order to secure lifespan and various electrochemical performances by doping lithium metal oxide, selection of the doping element is important. Doping elements known to date include, for example, monovalent ions such as Ag ⁺ and Na ⁺ and Co ²⁺ , Cu ²⁺ , Mg ²⁺ , Zn ²⁺ , Ba ²⁺ , and Al ³⁺ , Fe ³⁺ , Cr ³⁺ , Ga ³⁺ , Zr ⁴⁺ , Ti ⁴⁺ and other multivalent ions of two or more valences. Each of these elements has different effects on the lifespan and output characteristics of the battery.

In this embodiment, by including Al, Nb, B, Zr, and Ti among these doping elements, high capacity can be secured while improving room temperature and high temperature lifespan characteristics and thermal stability, and the initial resistance characteristics and resistance increase rate can be significantly reduced. there is.

Specifically, when Ti ⁴⁺ is doped into the NCM layered structure, it can stabilize the structure of the positive electrode active material by suppressing the movement of Ni ²⁺ to the Li site.

In addition, Al ³⁺ prevents Al ions from moving to the tetragonal lattice site and deteriorating the layered structure into a spinel structure. The layered structure facilitates removal and insertion of Li ions, but the sphenyl structure does not allow smooth movement of Li ions.

Zr ⁴⁺ acts as a kind of pillar because Zr ions occupy the Li site and stabilizes the layered structure by alleviating the contraction of the lithium ion path during the charging and discharging process. This phenomenon can increase cycle life by reducing cation mixing and increasing lithium diffusion coefficient.

Additionally, Nb can improve initial capacity and initial efficiency.

When doping B (Boron) with the above doping element, the initial resistance can be reduced by reducing the grain size during sintering of the positive electrode active material. In addition, lifespan characteristics and thermal decomposition temperature can be increased.

In this embodiment, the doping amount of Al may be in the range of 0.006 mole to 0.029 mole, more specifically, 0.0085 mole to 0.025 mole, based on 1 mole of the total of nickel, cobalt, manganese, and doping elements. When the Al content satisfies the above range, a lithium secondary battery with excellent initial efficiency and thermal stability and significantly improved lifespan at room temperature and high temperature can be implemented.

Next, the doping amount of Nb may be in the range of 0.00025 mole to 0.005 mole, more specifically, 0.0005 mole to 0.0025 mole, based on 1 mole of the total of nickel, cobalt, manganese, and doping elements. When the doping amount of Nb satisfies the above range, a very advantageous effect can be realized in that the room temperature life, high temperature life, resistance increase rate, and average leakage current value of the lithium secondary battery can all be improved. Additionally, the diffusion coefficient of the lithium secondary battery increases and the resistance increase rate during impedance analysis can be effectively reduced.

The doping amount of B may range from 0.001 mole to 0.015 mole, more specifically, from 0.005 mole to 0.01 mole, based on 1 mole of the total of nickel, cobalt, manganese, and doping elements. When the doping amount of B satisfies the above range, the initial resistance value can be reduced because the crystal grain size is reduced during sintering of the positive electrode active material, and the room temperature and high temperature lifespan characteristics and thermal decomposition temperature can be increased.

Next, the doping amount of Zr may be in the range of 0.001 mole to 0.007 mole, more specifically, 0.002 mole to 0.005 mole, or 0.0035 mole to 0.005 mole, based on 1 mole of the total of nickel, cobalt, manganese, and doping elements. When the Zr doping amount satisfies the above range, the high-temperature lifespan and room-temperature lifespan characteristics of a lithium secondary battery can be significantly improved.

The doping amount of Ti may be in the range of 0.0002 mole to 0.0015 mole, and specifically in the range of 0.0005 mole to 0.001 mole, based on 1 mole of the total of nickel, cobalt, manganese, and doping elements. When the doping amount of Ti satisfies the above range, excellent discharge capacity and efficiency can be secured, room temperature and high temperature lifespan characteristics can be improved, and resistance increase rate and average leakage current value can be reduced.

In this embodiment, the doping amounts of Nb, Al, and Zr may satisfy the relationship in Equation 1 below.

[Equation 1]

4 < ([Zr]+[Al])/[Nb] < 210

In Equation 1, [Nb], [Al], and [Zr] mean the doping amount of each element based on 1 mole of nickel, cobalt, manganese, and the total of the doping elements.

More specifically, Equation 1 may range from 5 to 70, or from 10 to 50.

When Equation 1 satisfies the above range, structural stability is improved and cycle characteristics and initial resistance increase rate are improved. .

Meanwhile, the doping amounts of Nb, Ti, and B may satisfy the relationship in Equation 2 below.

[Equation 2]

1 < ([B]+[Ti])/[Nb] < 40

In Equation 2, [Nb], [Ti], and [B] mean the doping amount of each element based on 1 mole of the total of nickel, cobalt, manganese, and doping elements.

More specifically, Equation 2 may range from 2 to 30, or from 3 to 15.

When Equation 2 satisfies the above range, initial resistance, initial capacity, and thermal stability are improved.

The positive electrode active material for a lithium secondary battery of this example may be expressed by the following formula (1).

[Formula 1]

Li _a [Ni _x Co _y Mn _z ] _1-t (Al _h Nb _i Zr _j B _k Ti _m ) _t O _{2- p}

In Formula 1,

X is one or more elements selected from the group containing F, N, and P,

a is 0.8 ≤ a ≤ 1.3,

t is 0.008 ≤ t ≤ 0.05,

0.6 ≤ x ≤ 0.95, 0 < y ≤ 0.2, 0 < z ≤ 0.2, 0.006 ≤ h ≤ 0.025, 0.00025 ≤ i ≤ 0.005, 0.001 ≤ j ≤ 0.007, 0.006 ≤ k ≤ 0.029, 0.0002 ≤ m ≤ 0.015, 0 ≤ p ≤ 0.02.

Additionally, the content of nickel in the metal oxide particles may be 0.8 mol or more and 0.99 mol or less, more specifically, 0.85 mol to 0.99 mol, based on 1 mol of the total of nickel, cobalt, and manganese.

As in this embodiment, when the nickel content in the metal oxide is 0.8 mol or more per 1 mol of total nickel, cobalt, and manganese, a positive electrode active material with high output characteristics can be implemented. The positive electrode active material of this example having this composition has a higher energy density per volume, so it can improve the capacity of the battery to which it is applied, and is also suitable for use in electric vehicles.

Meanwhile, the initial diffusion coefficient of the positive electrode active material according to this embodiment ranges from 6.91*10 ^-9 m ² /sec to 7.58*10 ^-9 m ² /sec, more specifically 7.03*10 ^-9 m ² /sec to 7.58* 10 ^-9 m ² /sec, and more preferably 7.33*10 ^-9 m ² /sec to 7.58*10 ^-9 m ² /sec. When the initial diffusion coefficient satisfies the above range, the movement of Li ions in the positive electrode active material is effective, and this increases the initial capacity and rate characteristics of the positive electrode material. On the other hand, if the diffusion coefficient is less than 6.91*10 ^-9 m ² /sec, the resistance within the positive electrode active material increases, which significantly reduces the cycle characteristics. If the diffusion coefficient exceeds 7.58*10 ^-9 m ² /sec, the resistance is improved and the capacity improvement effect is good, but structural instability increases and cycle characteristics deteriorate.

Next, the crystal grain size of the metal oxide particles may range from 1,036 Å to 1,440 Å, and more specifically, from 1,036 Å to 1,086 Å. When the grain size satisfies the above range, high temperature life is improved without reducing initial capacity.

As a limit, the full width at half maximum (FWHM) value for the (110) plane of the metal oxide particle may be in the range of 0.126 to 0.204, more specifically in the range of 0.170 to 0.204. When the full width at half maximum (FWHM) value for the (110) plane satisfies the above range, the high temperature lifespan is significantly improved.

When measuring an

Generally, the peak intensity value refers to the height value of the peak or the integrated area value obtained by integrating the area of the peak, and in this embodiment, the peak intensity value refers to the area value of the peak.

When the peak intensity ratio I(003)/I(104) is within the above range, structural stabilization is improved without a decrease in capacity, and the thermal safety of the positive electrode active material can be improved.

In addition, the peak intensity ratio I(003)/I(104) is a cation mixing index, and if the I(003)/I(104) value decreases, the initial capacity and rate characteristics of the positive electrode active material may decrease. You can. However, in this embodiment, I(003)/I(104) satisfies the range of 1.186 to 1.204, so a positive electrode active material with excellent capacity and rate characteristics can be implemented.

Meanwhile, the positive electrode active material of this embodiment may be in a bi-modal form in which large-diameter particles and small-diameter particles are mixed. The large particle size particles may have an average particle diameter (D50) in the range of 10㎛ to 20㎛, and the small particle size particles may have an average particle size (D50) in the range of 3㎛ to 7㎛. At this time, of course, the large-diameter particles and the small-diameter particles may also be in the form of secondary particles in which at least one primary particle is assembled. Additionally, the mixing ratio of large-diameter particles and small-diameter particles may be 50 to 80% by weight of large-diameter particles based on 100% by weight of the total. This bimodal particle distribution can improve energy density.

In another embodiment of the present invention, a lithium secondary battery is provided including a positive electrode including a positive electrode active material according to an embodiment of the present invention described above, a negative electrode including a negative electrode active material, and an electrolyte located between the positive electrode and the negative electrode. do.

The description related to the positive electrode active material will be omitted since it is the same as the embodiment of the present invention described above.

The positive active material layer may include a binder and a conductive material.

The binder serves to adhere the positive electrode active material particles to each other and also to adhere the positive electrode active material to the current collector.

The conductive material is used to provide conductivity to the electrode, and in the battery being constructed, any electronically conductive material can be used as long as it does not cause chemical change.

The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector, and the negative electrode active material layer includes a negative electrode active material.

The negative electrode active material includes a material capable of reversibly intercalating/deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

The material capable of reversibly intercalating/deintercalating lithium ions is a carbon material. Any carbon-based anode active material commonly used in lithium ion secondary batteries can be used, and a representative example is crystalline carbon. , amorphous carbon, or a combination of these can be used.

The lithium metal alloy includes lithium and Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn. Any alloy of metals of choice may be used.

Materials capable of doping and dedoping lithium include Si, _SiO It is an element selected from the group consisting of rare earth elements and combinations thereof, but not Si), Sn, SnO ₂ , Sn-Y (Y is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth elements selected from the group consisting of elements and combinations thereof, but not Sn).

Examples of the transition metal oxide include vanadium oxide and lithium vanadium oxide. The anode active material layer also includes a binder and, optionally, may further include a conductive material.

The binder serves to adhere the negative electrode active material particles to each other and also helps the negative electrode active material to adhere to the current collector.

The conductive material is used to provide conductivity to the electrode, and in the battery being constructed, any electronically conductive material can be used as long as it does not cause chemical change.

The current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

The negative electrode and positive electrode are manufactured by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and applying this composition to a current collector. Since this electrode manufacturing method is widely known in the field, detailed description will be omitted in this specification. The solvent may be N-methylpyrrolidone, but is not limited thereto.

The electrolyte includes a non-aqueous organic solvent and a lithium salt.

The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

The lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions in the battery, enabling the basic operation of a lithium secondary battery and promoting the movement of lithium ions between the anode and the cathode.

Depending on the type of lithium secondary battery, a separator may exist between the positive and negative electrodes. Such separators may be polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof, such as polyethylene/polypropylene two-layer separator, polyethylene/polypropylene/polyethylene three-layer separator, polypropylene/polyethylene/poly. Of course, a mixed multilayer film such as a propylene three-layer separator can be used.

Lithium secondary batteries can be classified into lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries depending on the type of separator and electrolyte used, and can be classified into cylindrical, prismatic, coin, pouch, etc. depending on their shape. Depending on the size, it can be divided into bulk type and thin film type. The structures and manufacturing methods of these batteries are widely known in this field, so detailed descriptions are omitted.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of the claims to be described later.

Preparation Example 1 - Preparation of NCM precursor

The positive electrode active material precursor was prepared by a general coprecipitation method.

NiSO ₄ ·6H ₂ O was used as a nickel raw material, CoSO ₄ ·7H ₂ O was used as a cobalt raw material, and MnSO ₄ ·H ₂ O was used as a manganese raw material. These raw materials were dissolved in distilled water to prepare an aqueous metal salt solution.

After preparing the coprecipitation reactor, N ₂ was purged to prevent oxidation of metal ions during the coprecipitation reaction, and the reactor temperature was maintained at 50°C.

NH ₄ (OH) was added as a chelating agent to the coprecipitation reactor, and NaOH was used to adjust pH. The precipitate obtained through the coprecipitation process was filtered, washed with distilled water, and dried in a cake dryer at 180°C to prepare a positive electrode active material precursor.

The composition of the prepared precursor was (Ni _0.92 Co _0.04 Mn _0.04 )(OH) ₂ , the average particle diameter (D50) of the large-diameter precursor was 14.3㎛, and the average particle diameter (D50) of the small-diameter precursor was 4.5㎛.

Example 1 - 0.0035 mol Zr + 0.015 mol Al + 0.0001 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A mixture of the precursor, lithium raw material, and doping raw material prepared in Preparation Example 1 was fired in an oxygen atmosphere in a tube furnace. The firing conditions were maintained at 480 ^o C for 5 hours, followed by 15 hours at 740-780 ^o C, and the temperature increase rate was 5 ^o C/min.

The lithium raw material used was LiOH·H ₂ O (Samchun Chemical, battery grade), and the doping raw materials were ZrO ₂ (Aldrich, 3N), Al(OH) ₃ (Aldrich, 3N), and TiO ₂ (Aldrich, 3N), H ₃ BO ₃ (Aldrich, 3N), and Nb ₂ O ₅ (Aldrich, 3N) were used.

At this time, the doping amount was expressed as M = Ni _0.92 Co _0.04 Mn _0.04 based on LiNi _0.92 Co _0.04 Mn _0.04 O ₂ that was not doped with metal elements, and the input amount of doping raw materials was adjusted so that the total of M and doped amount was 1 mol. . In other words, it has a structure of Li(M) _1-x (D) _x O ₂ (M=NCMA, D=doping material). The overall composition of the large- and small-diameter positive active materials doped with five types of elements prepared in this way was Li(M) _0.9704 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.0001 O ₂ .

The calcined large particle size and small particle size positive electrode active materials were uniformly mixed at a weight ratio of 80:20 (large particle size: small particle size) to prepare the positive electrode active material of Example 1 in a bi-modal form.

Example 2 - 0.0035 mol Zr + 0.015 mol Al + 0.00025 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 2 was Li(M) _0.97025 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.00025 O ₂ .

Example 3 - 0.0035 mol Zr + 0.015 mol Al + 0.0005 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 3 was Li(M) _0.97 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.0005 O ₂ .

Example 4 - 0.0035 mol Zr + 0.015 mol Al + 0.001 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 4 was Li(M) _0.9695 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.001 O ₂ .

Example 5 - 0.0035 mol Zr + 0.015 mol Al + 0.0025 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 5 was Li(M) _0.968 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Reference Example 1 - 0.0035 mol Zr+0.015 mol Al+0.005 mol Nb+0.01 mol B+0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Reference Example 1 was Li(M) _0.9655 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.005 O ₂ .

Reference Example 2 - 0.0035 mol Zr + 0.015 mol Al + 0.01 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Reference Example 2 was Li(M) _0.9605 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.01 O ₂ .

Example 6 - 0.002 mol Zr + 0.015 mol Al + 0.0025 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 6 was Li(M) _0.9719 Zr _0.002 Al _0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Example 7 - 0.005 mol Zr + 0.015 mol Al + 0.0025 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 7 was Li(M) _0.9665 Zr _0.005 Al _0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Reference Example 3 - 0.008 mol Zr + 0.015 mol Al + 0.0025 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was manufactured in the same manner as in Example 1, except that the amounts of aluminum raw material and doping raw material were adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Reference Example 3 was Li(M) _0.9635 Zr _0.008 Al _0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Reference Example 4 - 0.0035 mol Zr + 0.005 mol Al + 0.0025 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Reference Example 4 was Li(M) _0.978 Zr _0.0035 Al _0.005 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Example 8 - 0.0035 mol Zr + 0.0085 mol Al + 0.0025 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 8 was Li(M) _0.9745 Zr _0.0035 Al _0.0085 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Example 9 - 0.0035 mol Zr + 0.02 mol Al + 0.0025 mol Nb + 0.01 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 9 was Li(M) _0.963 Zr _0.0035 Al _0.02 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Reference Example 5 - 0.0035 mol Zr+0.025 mol Al+0.0025 mol Nb+0.01 mol B+0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Reference Example 3 was Li(M) _0.958 Zr _0.0035 Al _0.025 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Reference Example 6 - 0.0035 mol Zr+0.015 mol Al+0.0025 mol Nb+0.01 mol B+0.0001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Reference Example 6 was Li(M) _0.9689 Zr _0.0035 Al _0.015 Ti _0.0001 B _0.01 Nb _0.0025 O ₂ .

Example 10 - 0.0035 mol Zr + 0.015 mol Al + 0.0025 mol Nb + 0.01 mol B + 0.0005 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 10 was Li(M) _0.9685 Zr _0.0035 Al _0.015 Ti _0.0005 B _0.01 Nb _0.0025 O ₂ .

Example 11 - 0.0035 mol Zr + 0.015 mol Al + 0.0025 mol Nb + 0.01 mol B + 0.0015 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 11 was Li(M) _0.9675 Zr _0.0035 Al _0.015 Ti _0.0015 B _0.01 Nb _0.0025 O ₂ .

Reference Example 7 - 0.0035 mol Zr+0.015 mol Al+0.0025 mol Nb+0.01 mol B+0.002 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Reference Example 7 was Li(M) _0.967 Zr _0.0035 Al _0.015 Ti _0.002 B _0.01 Nb _0.0025 O ₂ .

Reference Example 8 - 0.0035 mol Zr + 0.015 mol Al + 0.0025 mol Nb + 0.001 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Reference Example 8 was Li(M) _0.977 Zr _0.0035 Al _0.015 Ti _0.001 B _0.001 Nb _0.0025 O ₂ .

Example 12 - 0.0035 mol Zr + 0.015 mol Al + 0.0025 mol Nb + 0.005 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Example 12 was Li(M) _0.973 Zr _0.0035 Al _0.015 Ti _0.001 B _0.005 Nb _0.0025 O ₂ .

Reference Example 9 - 0.0035 mol Zr + 0.015 mol Al + 0.0025 mol Nb + 0.015 mol B + 0.001 mol Ti doping

A bimodal positive electrode active material was prepared in the same manner as in Example 1, except that the amount of the doping raw material was adjusted using the precursor prepared in Preparation Example 1.

The overall composition of the positive electrode active material prepared according to Reference Example 9 was Li(M) _0.963 Zr _0.0035 Al _0.015 Ti _0.001 B _0.015 Nb _0.0025 O ₂ .

The doping amount and overall composition of the positive electrode active materials prepared according to Comparative Example 1, Examples 2 to 12, and Reference Examples 1 to 9 are shown in the table below.

division doping element Total active material composition Al Zr Nb B Ti Example 1 0.015 0.0035 0.0001 0.01 0.001 Li(M) _0.9704 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.0001 O ₂ Comparative Example 1 0.015 0.0035 0 0.01 0.001 Li(M) _0.9705 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 O ₂ Example 2 0.015 0.0035 0.00025 0.01 0.001 Li(M) _0.97025 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.00025 O ₂ Example 3 0.015 0.0035 0.0005 0.01 0.001 Li(M) _0.97 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.0005 O ₂ Example 4 0.015 0.0035 0.001 0.01 0.001 Li(M) _0.9695 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.001 O ₂ Example 5 0.015 0.0035 0.0025 0.01 0.001 Li(M) _0.968 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ Reference example 1 0.015 0.0035 0.005 0.01 0.001 Li(M) _0.9655 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.005 O ₂ Reference example 2 0.015 0.0035 0.01 0.01 0.001 Li(M) _0.9605 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.01 O ₂ Example 6 0.015 0.002 0.0025 0.01 0.001 Li(M) _0.9695 Zr _0.002 Al _0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ Example 7 0.015 0.005 0.0025 0.01 0.001 Li(M) _0.9665 Zr _0.005 Al _0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ Reference example 3 0.015 0.008 0.0025 0.01 0.001 Li(M) _0.9635 Zr _0.008 Al _0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ Reference example 4 0.005 0.0035 0.0025 0.01 0.001 Li(M) _0.978 Zr _0.0035 Al _0.005 Ti _0.001 B _0.01 Nb _0.0025 O ₂ Example 8 0.0085 0.0035 0.0025 0.01 0.001 Li(M) _0.9745 Zr _0.0035 Al _0.0085 Ti _0.001 B _0.01 Nb _0.0025 O ₂ Example 9 0.02 0.0035 0.0025 0.01 0.001 Li(M) _0.963 Zr _0.0035 Al _0.02 Ti _0.001 B _0.01 Nb _0.0025 O ₂ Reference example 5 0.025 0.0035 0.0025 0.01 0.001 Li(M) _0.958 Zr _0.0035 Al _0.025 Ti _0.001 B _0.01 Nb _0.0025 O ₂ Reference example 6 0.015 0.0035 0.0025 0.01 0.0001 Li(M) _0.9689 Zr _0.0035 Al _0.015 Ti _0.0001 B _0.01 Nb _0.0025 O ₂ Example 10 0.015 0.0035 0.0025 0.01 0.0005 Li(M) _0.9685 Zr _0.0035 Al _0.015 Ti _0.0005 B _0.01 Nb _0.0025 O ₂ Example 11 0.015 0.0035 0.0025 0.01 0.0015 Li(M) _0.9675 Zr _0.0035 Al _0.015 Ti _0.0015 B _0.01 Nb _0.0025 O ₂ Reference example 7 0.015 0.0035 0.0025 0.01 0.002 Li(M) _0.976 Zr _0.0035 Al _0.015 Ti _0.002 B _0.01 Nb _0.0025 O ₂ Reference example 8 0.015 0.0035 0.0025 0.001 0.001 Li(M) _0.977 Zr _0.0035 Al _0.015 Ti _0.001 B _0.001 Nb _0.0025 O ₂ Example 12 0.015 0.0035 0.0025 0.005 0.001 Li(M) _0.973 Zr _0.0035 Al _0.015 Ti _0.001 B _0.005 Nb _0.0025 O ₂ Reference example 9 0.015 0.0035 0.0025 0.015 0.001 Li(M) _0.963 Zr _0.0035 Al _0.015 Ti _0.001 B _0.015 Nb _0.0025 O ₂

Comparative Example 2 - 0.8 mol Ni+0.0035 mol Zr+0.015 mol Al+0.01 mol B+0.001 mol Ti doping

Large particle size and small particle size precursors having the composition (Ni _0.80 Co _0.10 Mn _0.10 )(OH) ₂ were prepared in the same manner as Preparation Example 1.

Next, a bimodal positive electrode active material was manufactured in the same manner as Example 1, except that the amount of doping raw material was adjusted using the precursor.

The overall composition of the positive electrode active material prepared according to Comparative Example 2 was Li(Ni _0.80 Co _0.10 Mn _0.10 ) _0.9705 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 O ₂ .

Comparative Example 3 - 0.83 mol Ni+0.0035 mol Zr+0.015 mol Al+0.01 mol B+0.001 mol Ti doping

Large particle size and small particle size precursors having the composition (Ni _0.83 Co _0.12 Mn _0.05 )(OH) ₂ were prepared in the same manner as Preparation Example 1.

Next, a bimodal positive electrode active material was manufactured in the same manner as Example 1, except that the amount of doping raw material was adjusted using the precursor.

The overall composition of the positive electrode active material prepared according to Comparative Example 3 was Li(Ni _0.83 Co _0.12 Mn _0.05 ) _0.9705 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 O ₂ .

Comparative Example 4 - 0.85 mol Ni+0.0035 mol Zr+0.015 mol Al+0.01 mol B+0.001 mol Ti doping

Large-diameter and small-diameter precursors having the composition (Ni _0.85 Co _0.075 Mn _0.075 )(OH) ₂ were prepared in the same manner as Preparation Example 1.

Next, a bimodal positive electrode active material was manufactured in the same manner as Example 1, except that the amount of doping raw material was adjusted using the precursor.

The overall composition of the positive electrode active material prepared according to Comparative Example 4 was Li(Ni _0.85 Co _0.075 Mn _0.075 ) _0.9705 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 O ₂ .

Comparative Example 5 - 0.86 mol Ni+0.0035 mol Zr+0.015 mol Al+0.01 mol B+0.001 mol Ti doping

Large-diameter and small-diameter precursors having the composition (Ni _0.86 Co _0.07 Mn _0.07 ) (OH) ₂ were prepared in the same manner as Preparation Example 1.

Next, a bimodal positive electrode active material was manufactured in the same manner as Example 1, except that the amount of doping raw material was adjusted using the precursor.

The overall composition of the positive electrode active material prepared according to Comparative Example 5 was Li(Ni _0.86 Co _0.06 Mn _0.06 ) _0.9705 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 O ₂ .

Comparative Example 6 - 0.88 mol Ni+0.0035 mol Zr+0.015 mol Al+0.01 mol B+0.001 mol Ti doping

Large particle size and small particle size precursors having the composition (Ni _0.88 Co _0.05 Mn _0.07 ) (OH) ₂ were prepared in the same manner as Preparation Example 1.

Next, a bimodal positive electrode active material was manufactured in the same manner as Example 1, except that the amount of doping raw material was adjusted using the precursor.

The overall composition of the positive electrode active material prepared according to Comparative Example 6 was Li(Ni _0.88 Co _0.05 Mn _0.07 ) _0.9705 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 O ₂ .

Reference Example 10 - 0.8 mol Ni+same doping as Example 5

Large particle size and small particle size precursors having the composition (Ni _0.80 Co _0.10 Mn _0.10 )(OH) ₂ were prepared in the same manner as Preparation Example 1.

Next, a bimodal positive electrode active material was prepared in the same manner as Example 5, except that the precursor was used.

The overall composition of the positive electrode active material prepared according to Reference Example 10 was Li(Ni _0.80 Co _0.10 Mn _0.10 ) _0.968 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Reference Example 11 - 0.83 mol Ni+same doping as Example 5

Large particle size and small particle size precursors having the composition (Ni _0.83 Co _0.12 Mn _0.05 )(OH) ₂ were prepared in the same manner as Preparation Example 1.

Next, a bimodal positive electrode active material was prepared in the same manner as Example 5, except that the precursor was used.

The overall composition of the positive electrode active material prepared according to Reference Example 11 was Li(Ni _0.83 Co _0.12 Mn _0.05 ) _0.968 Zr _0.0035 Al _0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Example 13 - 0.85 mol Ni+same doping as Example 5

Large particle size and small particle size precursors having the composition (Ni _0.85 Co _0.07 Mn _0.08 ) (OH) ₂ were prepared in the same manner as Preparation Example 1.

Next, a bimodal positive electrode active material was prepared in the same manner as Example 5, except that the precursor was used.

The overall composition of the positive electrode active material prepared according to Example 13 was Li(Ni _0.85 Co _0.07 Mn _0.08 ) _{0.968 Zr 0.0035} Al _{0.015 Ti 0.001} B _0.01 Nb _0.0025 O ₂ .

Example 14 - 0.86 mol Ni+same doping as Example 5

Large-diameter and small-diameter precursors having the composition (Ni _0.86 Co _0.07 Mn _0.07 ) (OH) ₂ were prepared in the same manner as Preparation Example 1.

Next, a bimodal positive electrode active material was prepared in the same manner as Example 5, except that the precursor was used.

The overall composition of the positive electrode active material prepared according to Example 14 was Li(Ni _0.86 Co _0.07 Mn _0.07 ) _{0.968 Zr 0.0035} Al 0.015 Ti _0.001 B _0.01 Nb _0.0025 O ₂ .

Example 15 - 0.88 mol Ni+same doping as Example 5

Large particle size and small particle size precursors having the composition (Ni _0.88 Co _0.05 Mn _0.07 ) (OH) ₂ were prepared in the same manner as Preparation Example 1.

Next, a bimodal positive electrode active material was prepared in the same manner as Example 5, except that the precursor was used.

The overall composition of the positive electrode active material prepared according to Example 15 was Li(Ni _0.88 Co _0.05 Mn _0.07 ) _0.968 Zr _0.0035 Al _{0.015 Ti 0.001 B 0.01} Nb _0.0025 O ₂ .

The precursor composition and doping amount of the positive electrode active material prepared according to Comparative Examples 2 to 6, Examples 13 to 15, and Reference Examples 10 to 11 are shown in the table below.

division Precursor composition doping element Al Zr Nb B Ti Comparative Example 2 (Ni _0.80 Co _0.10 Mn _0.10 )(OH) ₂ 0.015 0.0035 - 0.01 0.001 Comparative Example 3 (Ni _0.83 Co _0.12 Mn _0.05 )(OH) ₂ 0.015 0.0035 - 0.01 0.001 Comparative Example 4 (Ni _0.85 Co _0.075 Mn _0.075 )(OH) ₂ 0.015 0.0035 - 0.01 0.001 Comparative Example 5 (Ni _0.86 Co _0.07 Mn _0.07 )(OH) ₂ 0.015 0.0035 - 0.01 0.001 Comparative Example 6 (Ni _0.88 Co _0.05 Mn _0.07 )(OH) ₂ 0.015 0.0035 - 0.01 0.001 Reference example 10 (Ni _0.80 Co _0.10 Mn _0.10 )(OH) ₂ 0.015 0.0035 0.0025 0.01 0.001 Reference example 11 (Ni _0.83 Co _0.12 Mn _0.05 )(OH) ₂ 0.015 0.0035 0.0025 0.01 0.001 Example 13 (Ni _0.85 Co _0.075 Mn _0.075 )(OH) ₂ 0.015 0.0035 0.0025 0.01 0.001 Example 14 (Ni _0.86 Co _0.07 Mn _0.07 )(OH) ₂ 0.015 0.0035 0.0025 0.01 0.001 Example 15 (Ni _0.88 Co _0.05 Mn _0.07 )(OH) ₂ 0.015 0.0035 0.0025 0.01 0.001

Experimental Example 1 - XRD analysis results

The lattice constants of the positive electrode active materials prepared according to Examples 1 to 5, Reference Examples 1 to 2, and Comparative Example 1 were obtained by X-ray diffraction measurement using CuKα rays. The measured a-axis length, b-axis length, and c-axis length are shown in Table 1 below.

Additionally, the unit cell volume and crystalline size of the active material were measured and shown in Table 1 below.

Next, for crystallographic examination by doping, Rietveld analysis was performed using the commercial software High Score Plus 4.0 program, and the results are shown in Table 1. The XRD measurement range was performed from 10 ^o to 130 ^o , and fitting was performed through Rietveld refinement. The GOF (Goodness of Fitness) value matched within 2.0.

The intensity (peak area) of the (003) and (104) planes and the intensity of the (110) plane were measured at a scan speed (°/s) of 0.328 using From these results, the full width at half maximum (FWHM) of the I(003)/I(104) and (110) planes was calculated and shown in Table 1.

In addition, in all of the measured samples, the (003) plane was well developed as the main peak around 18.7 ^o , the (006)/(102) peak between 37.5 ^o and 38.5 ^o , and the (108)/(110) peak between 63.5 ^o and 35.5 ^o . As it was confirmed that splitting of the peak appeared, it was found that the hexagonal layer had good crystalline ordering and that it exhibited a typical α-NaFeO ₂ (space group R-3m) structure.

division a b c unit cell volume I(003)/
I(104)
(Strength standard) I(003)/
I(104)
(based on area) (110) FWHM grain size
(Å) Comparative Example 1 2.8720 2.8720 14.1875 101.3783 1.185 1.081 0.126 1460 Example 1 2.8723 2.8723 14.1891 101.3946 1.186 1.082 0.126 1440 Example 2 2.8725 2.8725 14.1894 101.5708 1.189 1.085 0.149 1200 Example 3 2.8738 2.8738 14.2012 101.6231 1.201 1.096 0.170 1086 Example 4 2.8744 2.8744 14.2026 101.6979 1.215 1.108 0.188 1065 Example 5 2.8752 2.8752 14.2054 101.6613 1.204 1.098 0.204 1036 Reference example 1 2.8750 2.8750 14.2020 101.6493 1.214 1.107 0.224 786 Reference example 2 2.8748 2.8748 14.2023 101.3783 1.211 1.105 0.254 663

Referring to Table 3, it can be seen that the crystal structure parameter values change as a result of XRD analysis depending on the doping element and doping amount.

Specifically, compared to the positive electrode active material of Comparative Example 1 in which NCM active material was doped with Zr, Al, Ti, and B, Examples 1 to 5 and Reference Examples 1 to 5 in which NCM was doped with Zr, Nb, Ti, B, and NB. It can be seen that the FWHM value of the (110) plane of 2 increases and the grain size decreases. In addition, it was found that the crystal structure constants a and b had the maximum value in Example 4, and the c value had the maximum value in Example 5. It was found that the unit cell volume also had the maximum value in Example 4. The intensity ratio and area ratio of (003)/(104), which represents the cation mixing index, tend to be the highest in Example 3, so doping of an appropriate amount of Nb suppresses cation mixing. You can see that it has an effect.

That is, in this example, it can be confirmed that the doping amount of Nb may be in the range of 0.0001 mole to 0.005 mole, and is preferably in the range of 0.0001 mole to 0.0025 mole, based on 1 mole of the total of nickel, cobalt, manganese, and doping elements. there is.

Experimental Example 2 - Electrochemical Evaluation

(1) Manufacturing of coin-type half cells

A CR2032 coin cell was manufactured using the positive electrode active material prepared as above, and then electrochemical evaluation was performed.

Specifically, the positive electrode active material, conductive material (Denka Black), and polyvinylidene fluoride binder (Product name: KF1100) were mixed at a weight ratio of 92.5:3.5:4, and this mixture was mixed with N-methyl so that the solid content was about 30% by weight. A positive electrode active material slurry was prepared by adding -2-pyrrolidone (N-Methyl-2-pyrrolidone) to the solvent.

The slurry was coated on aluminum foil (thickness: 15 ㎛), which is a positive electrode current collector, using a doctor blade, dried, and rolled to prepare a positive electrode. The loading amount of the positive electrode was about 14.6 mg/cm 2 and the rolling density was about 3.1 g/cm ³ .

A 2032 coin-type half cell was manufactured by a conventional method using the positive electrode, lithium metal negative electrode (thickness 300 μm, MTI), electrolyte, and polypropylene separator. The electrolyte solution was prepared by dissolving 1M LiPF ₆ in a mixed solvent of ethylene carbonate, dimethyl carbonate, and ethylmethyl carbonate (EMC) (mixing ratio EC:DMC:EMC=3:4:3% by volume) to prepare a mixed solution, and then adding vinyl to it. 3% by weight of lene carbonate (VC) was added and used.

(2) Evaluation of charge/discharge characteristics

The coin-type half-cell manufactured in (1) above was aged at room temperature (25°C) for 10 hours, and then a charge/discharge test was performed.

For capacity evaluation, 205mAh/g was used as the standard capacity, and the charging and discharging conditions were constant current (CC) / constant voltage (CV) 2.5V to 4.25V and 1/20C cut-off.

The initial capacity was measured after 0.1C charge/0.1C discharge, and after 0.2C charge/0.2C discharge, the initial efficiency was calculated and the results are shown in Table 2 below.

(3) Measurement of life characteristics

The room temperature cycle life characteristics were measured at room temperature (25 ^o C), and the high temperature cycle life characteristics were measured 30 times at high temperature (45 ^o C) under 0.3C charge/0.3C discharge conditions.

(4) Measurement of resistance characteristics

The room temperature initial resistance (DC-IR (Direct current internal resistance)) is calculated by charging the battery at 25°C and discharging at 0.2C and 0.2C under constant current-constant voltage 2.5V to 4.25V and 1/20C cut-off conditions. This was performed once, and the voltage value was measured 60 seconds after applying the discharge current at 4.25V charging at 100%, and then calculated.

The resistance increase rate was measured in the same manner as the initial resistance measurement method after 30 cycle life compared to the resistance initially measured at room temperature (25°C) (room temperature initial resistance), and the increase rate was converted into percentage (%).

Average leakage current was measured by measuring the current generation over 120 hours when half a cell was maintained at 4.7V at a high temperature of 45°C and calculating the average value of the values.

(5) Thermal stability evaluation

Differential scanning calorimetry (DSC) analysis was prepared by charging the half-cell to 4.25V under initial 0.1C charging conditions, then disassembling the half-cell to obtain the positive electrode separately, and washing the positive electrode with dimethyl carbonate five times. . After impregnating the cleaned anode in a DSC crucible with an electrolyte, the temperature was raised to 265°C, and the change in calorific value was measured using a DSC1 star system from Mettler Toledo as a DSC instrument, showing the obtained DSC peak temperature.

Experimental Example 2-1. Effect depending on B content

The electrochemical property evaluation results performed by the method of Experimental Example 2 for the positive electrode active materials prepared according to Examples 1 to 5, Reference Examples 1 to 2, and Comparative Example 1 are shown in Table 4 below.

Discharge capacity
(mAh/g) initial efficiency
(%) Room temperature life
(%) High temperature life
(%) Room temperature initial resistance
(Ω) Resistance increase rate
(%) Average leakage current
(mA) DSC peak temperature
( ^o C) Comparative Example 1 215.5 90.1 88.7 85.7 26.5 91.2 0.34 227 Example 1 217.1 91.9 90.8 90.4 25.4 88.7 0.30 227 Example 2 217.5 92.1 92.1 91.0 23.1 78.6 0.30 227 Example 3 221.0 94.5 93.2 93.0 22.4 47.2 0.22 231 Example 4 222.4 94.6 96.1 95.0 22.5 45.5 0.21 230 Example 5 226.8 94.9 94.8 94.5 22.4 69.8 0.20 230 Reference example 1 214.0 92.1 90.1 88.7 24.6 155.7 0.20 230 Reference example 2 210.6 88.7 77.6 71.3 30.1 317.1 0.21 235

Examples 1 to 5 and Reference Examples 1 to 2 are the results of measuring electrochemical properties according to the doping amount when Zr, Nb, Ti, B, and Nb were doped together in a precursor with a Ni content of 90 mol% or more.

Referring to Table 4, the positive electrode active materials of Examples 1 to 5 in which the NCM precursor was doped with five types of elements, that is, Zr, Nb, Ti, B, and Nb, were compared to the NCM precursor with Zr, Nb, Ti, and B. Compared to the positive electrode active material in Example 1, it can be seen that discharge capacity, initial efficiency, room temperature life, high temperature life, room temperature resistance, resistance increase rate, leakage current, and DSC peak temperature are effectively improved.

However, the discharge capacity of the positive electrode active material of Reference Example 1 doped with 0.005 mol of Nb decreased and the resistance increase rate significantly increased. In addition, it can be seen that the discharge capacity, initial efficiency, room temperature life, and high temperature life of the positive electrode active material of Reference Example 2 doped with 0.01 mol of Nb are significantly reduced.

Therefore, in this embodiment, the doping amount of Nb is in the range of 0.00025 mole to 0.005 mole, more specifically, 0.0005 mole to 0.0025 mole, based on 1 mole of metal oxide containing nickel, cobalt, manganese, and doping elements, as described above. It can be confirmed that it is desirable.

Experimental Example 2-2. Effect depending on Zr content

The results of electrochemical property evaluation performed by the method of Experimental Example 2 on the positive electrode active materials prepared according to Examples 6 to 7 and Reference Example 3 are shown in Table 5 below. For comparison, the results of Example 4 are also shown.

Discharge capacity
(mAh/g) initial efficiency
(%) Room temperature life
(%) High temperature life
(%) Room temperature initial resistance
(Ω) Resistance increase rate
(%) Average leakage current
(mA) DSC peak temperature
( ^o C) Example 6 223.2 94.8 93.1 93.4 24.5 69.7 0.24 227 Example 4 222.4 94.6 96.1 95.0 22.5 45.5 0.21 230 Example 7 220.1 93.4 96.7 96.1 27.8 43.5 0.20 230 Reference example 3 210.3 87.4 97.6 97.1 32.2 65.8 0.20 230

In Examples 6 to 7 and Reference Example 3, the doping amount of Zr was fixed at 0.015 mol, 0.0025 mol, 0.01 mol, and 0.0025 mol of Nb. It's just changed.

Referring to Table 5, it can be understood that as the doping amount of Zr increases from 0.002 mol to 0.008 mol, some properties improve and some properties deteriorate.

Specifically, referring to the results of Examples 4, 6, and 7, it can be seen that as the doping amount of Zr increases, the high temperature lifespan and room temperature lifespan improve. However, it can be seen that when the Zr doping amount is increased to 0.008 mol as in Reference Example 3, the discharge capacity and initial efficiency are greatly reduced.

Therefore, in this embodiment, the appropriate doping amount of Zr is in the range of 0.001 mole to 0.007 mole, and specifically may be in the range of 0.002 mole to 0.005 mole or 0.0035 mole to 0.005 mole, based on 1 mole of nickel, cobalt, manganese, and doping element. .

Experimental Example 2-3. Effect depending on Al content

The results of electrochemical property evaluation performed by the method of Experimental Example 2 on the positive electrode active materials prepared according to Examples 8 to 9 and Reference Examples 4 to 5 are shown in Table 6 below. For comparison, the results of Example 4 are also shown.

Discharge capacity
(mAh/g) initial efficiency
(%) Room temperature life
(%) High temperature life
(%) Room temperature initial resistance
(Ω) Resistance increase rate
(%) Average leakage current
(mA) DSC peak temperature
( ^o C) Reference example 4 225.1 95.0 90.5 89.7 30.5 92.4 0.56 222 Example 8 224.1 94.8 93.1 92.7 24.1 61.9 0.34 228 Example 4 222.4 94.6 96.1 95.0 22.5 45.5 0.21 230 Example 9 220.1 94.0 97.1 96.4 21.3 43.2 0.20 232 Reference example 5 212.3 86.3 97.5 97.3 20.3 40.1 0.18 235

In Examples 8 to 9 and Reference Examples 4 to 5, only the Al doping amount was changed while the doping amount was fixed at 0.0035 mol of Zr, 0.0025 mol of Nb, 0.01 mol of B, and 0.001 mol of Ti.

Referring to Table 4, it can be seen that as the amount of Al raw material increases, room temperature life and high temperature life greatly increase, and room temperature initial resistance, resistance increase rate, and leakage current decrease. In particular, the DSC peak temperature increased significantly.

However, in the case of Reference Example 4 in which the mixed Al doping amount was 0.005 mol, it can be seen that the high temperature lifespan was significantly reduced and the resistance increase rate was also increased. In addition, in the case of Reference Example 5 in which the Al doping amount was 0.025 mol, it can be seen that the discharge capacity was greatly reduced and the initial efficiency was also significantly reduced.

Therefore, in this embodiment, the doping amount of Al may be in the range of 0.006 mole to 0.029 mole, more specifically, 0.0085 mole to 0.025 mole, based on 1 mole of nickel, cobalt, manganese, and doping raw material.

Experimental Example 2-4. Effects depending on Ti content

The results of electrochemical property evaluation performed by the method of Experimental Example 2 on the positive electrode active materials prepared according to Examples 10 to 11 and Reference Examples 6 to 7 are shown in Table 7 below. For comparison, the results of Example 4 are also shown.

Discharge capacity
(mAh/g) initial efficiency
(%) Room temperature life
(%) High temperature life
(%) Room temperature initial resistance
(Ω) Resistance increase rate
(%) Average leakage current
(mA) DSC peak temperature
( ^o C) Reference example 6 222.5 94.7 94.0 93.7 27.9 110.2 0.81 229 Example 10 222.5 94.5 95.0 94.3 23.7 67.7 0.43 229 Example 4 222.4 94.6 96.1 95.0 22.5 45.5 0.21 230 Example 11 220.1 93.2 96.4 96.1 21.3 43.4 0.24 230 Reference example 7 215.1 87.1 97.1 96.4 20.1 44.2 0.27 230

The doping amounts of Examples 10 to 11 and Reference Examples 6 to 7 were fixed at 0.0035 mol of Zr, 0.015 mol of Al, 0.01 mol of B, and 0.0025 mol of Nb, and only the Ti doping amount was changed.

Referring to Table 7, it can be seen that as the Ti content increases, room temperature life, high temperature life, and resistance characteristics increase.

However, in the case of Reference Example 6 in which 0.0001 mol of Ti was doped, there was a problem in that the room temperature resistance greatly increased and the average leakage current also increased. In addition, in the case of Hole 7 doped with 0.002 mol of Ti, it can be seen that the discharge capacity is greatly reduced and the initial efficiency is also rapidly reduced.

Therefore, in this embodiment, the appropriate doping amount of Ti may be in the range of 0.0002 mole to 0.0015 mole, and specifically in the range of 0.0005 mole to 0.001 mole, based on 1 mole of nickel, cobalt, manganese, and doping elements.

Experimental Example 2-5. Effect depending on B content

The results of electrochemical property evaluation performed by the method of Experimental Example 2 on the positive electrode active materials prepared according to Example 12 and Reference Examples 8 to 9 are shown in Table 8 below. For comparison, the results of Example 4 are also shown.

Discharge capacity
(mAh/g) initial efficiency
(%) Room temperature life
(%) High temperature life
(%) Room temperature initial resistance
(Ω) Resistance increase rate
(%) Average leakage current
(mA) DSC peak temperature
( ^o C) Reference example 8 224.1 94.9 92.1 92.4 22.0 110.2 0.78 221 Example 12 223.7 94.7 94.2 94.3 22.1 68.8 0.24 228 Example 4 222.4 94.6 96.1 95.0 22.5 45.5 0.21 230 Reference example 9 217.1 88.4 96.5 96.1 28.1 41.0 0.20 230

The doping amounts of Example 12 and Reference Examples 8 to 9 were fixed at 0.0035 mol of Zr, 0.015 mol of Al, 0.001 mol of Ti, and 0.0025 mol of Nb, and only the B doping amount was changed.

Referring to Table 8, it can be seen that as the content of B increases, the general lifespan and resistance increase rate improve.

However, in the case of Reference Example 8 in which the doping amount of B is 0.001 mole, the room temperature resistance rapidly increases, and in the case of Reference Example 9 in which the doping amount of B is 0.015 mole, the discharge capacity significantly decreases.

Therefore, in this example, it can be confirmed that the doping amount of B may be in the range of 0.001 mole to 0.015 mole, and is preferably in the range of 0.005 mole to 0.01 mole, based on 1 mole of the total of nickel, cobalt, manganese, and doping elements.

Experimental Example 2-6. Effect of Ni content

The electrochemical property evaluation results performed by the method of Experimental Example 2 for the positive electrode active materials prepared according to Comparative Examples 2 to 6, Reference Examples 10 to 11, and Examples 13 to 15 are shown in Table 9 below. For comparison, the results of Comparative Example 1 and Example 5 are also displayed.

Discharge capacity
(mAh/g) initial efficiency
(%) Room temperature life
(%) High temperature life
(%) Room temperature initial resistance
(Ω) Resistance increase rate
(%) Average leakage current
(mA) Comparative Example 2 (Ni80%) 201.7 88.7 96.1 96.2 14.3 44.1 0.20 Reference example 10 199.5 87.6 97.7 96.1 16.2 43.2 0.21 Comparative Example 3 (Ni83%) 205.8 88.9 95.1 94.7 16.2 48.3 0.20 Reference example 11 204.9 88.4 95.3 95.1 20.1 49.2 0.24 Comparative Example 4 (Ni85%) 209.1 88.5 95.2 95.1 24.3 61.7 0.23 Example 13 212.3 90.3 96.3 96.2 22.1 45.3 0.21 Comparative Example 5 (Ni86%) 210.2 90.4 93.7 93.2 26.3 78.1 0.28 Example 14 213.5 92.6 96.1 95.9 22.4 48.3 0.23 Comparative Example 6 (Ni88%) 215.3 91.2 94.7 94.1 30.0 97.3 0.31 Example 15 220.7 93.4 96.3 96.1 24.2 45.7 0.21 Comparative Example 1 (Ni92%) 215.5 90.1 88.7 85.7 26.5 91.2 0.34 Example 5 226.8 94.9 94.8 94.5 22.4 69.8 0.20

Comparative Examples 1 to 6 are cases in which the NCM precursor was subjected to quaternary doping, and Reference Examples 10 to 11 and Examples 13 to 15 are positive electrode active materials in which the NCM precursor was subjected to 5 element doping.

Referring to Table 9, in the case of Reference Examples 10 and 11, when the Ni content is less than 85%, it can be seen that even with 5-element doping, the discharge capacity and initial efficiency decrease when Nb is added, so that it operates with some resistance. there is. However, referring to Examples 13 to 15, it can be seen that when the Ni content is 85% or more and quintonic doping including Nb is performed, the discharge capacity and initial efficiency are greatly increased.

Although the resistance characteristics of Nb itself are higher than the resistance that occurs when a small amount of Ni is included, they are lower than the resistance characteristics that appear as Ni increases, so they have the effect of offsetting the effect of a rapid increase in resistance that occurs at Ni85% or higher. I think there is. That is, in the case of high-nickel NCM anode materials, it is believed that the rapid increase in resistance caused by an increase in Ni can be suppressed to some extent by doping with Nb. As a result, the overall high temperature life and room temperature life are increased, and the resistance increase rate characteristics are also improved. In conclusion, it can be understood that when a product with a Ni content of 85% or more is doped with 5-element materials (Zr, Al, Ti, B, and Nb), the effect of increasing discharge capacity and initial efficiency is very excellent, and other physical properties are also improved overall. Therefore, it can be confirmed that the effect of the penta-based doping material of this example is maximized in the area of 85% or more Ni.

Experimental Example 3 - Diffusion coefficient and impedance analysis

Diffusion coefficient and impedance analysis were performed on the positive electrode active materials prepared according to Examples 1 to 5, Reference Examples 1 to 2, and Comparative Example 1, and are shown in Table 8 below.

The diffusion coefficient was measured using the GITT method, charged for 30 minutes and maintained for 50 minutes, and the data obtained at this time was analyzed using Equation 3 below.

[Equation 3]

In equation 2,

V _M : molar volume of positive electrode active material

A: Electrode area when measuring diffusion coefficient

F: Faraday constant

_ZLi : +1

_Io : 0.1C

x: Fraction of lithium present in the electrode

dE _s : Voltage change obtained in the holding period,

dE _t : Voltage change obtained in the charging section

t: time (sec)

Specifically, the molar volume of the positive electrode active material was calculated using the unit volume analyzed through XRD measurement results. A is the electrode area when measuring the diffusion coefficient. The coin cell used to measure the diffusion coefficient has an area of 1.538 cm ² . I _o means 0.1C current value. X can be calculated by assuming the entire charge/discharge section to be 100%. For example, x corresponding to the initial 30-minute charging section can be expressed as 0.05, x corresponding to the second 30-minute charging section can be expressed as 0.1, and x corresponding to the middle section can be expressed as 0.5.

Impedance analysis was performed using an impedance graph obtained at 3.7V and, like the diffusion coefficient, is shown in Table 10 below. When the obtained impedance value was separated into real and imaginary axes and a Nyquist plot was performed, the resulting figure was divided into two semicircular shapes and fitted to obtain R _sei and R _ct . At this time, the resistance value obtained by the semicircle created in the high frequency region was named R _sei , and the resistance value obtained by the semicircle created in the low frequency region was named R _ct to obtain the resistance value.

Initial diffusion coefficient (*10 ^-9 m ² /sec) Early
Rsei
(Ω) Early
Rct
(Ω) Diffusion coefficient after cycle
(*10 ⁹ m ² /sec) Rsei after cycle
(Ω) Rct after cycle
(Ω) Diffusion coefficient increase rate
(%) Rsei
Increase rate (%) Rct
growth rate
(5) Comparative Example 1 6.56 0.9 4.5 4.61 11.1 6.7 29.8 644 562 Example 1 6.91 1.1 4.3 5.36 10.9 5.5 22.5 400 423 Example 2 7.03 1.2 4.6 5.93 11.0 3.7 15.6 208 239 Example 3 7.33 1.5 4.7 6.53 9.7 3.0 10.9 100 131 Example 4 7.42 1.6 4.3 6.61 9.8 3.1 10.9 93.7 153 Example 5 7.58 1.8 4.6 6.75 9.5 2.9 11.0 61.1 139 Reference example 1 7.26 2.3 4.7 6.50 9.8 3.3 10.4 43.5 121 Reference example 2 6.16 3.4 4.8 5.70 11.6 4.0 7.5 17.6 118

Referring to Table 10, it can be seen that in the example in which Zr, Nb, B, Al, and Ti were used as doping elements, the rate of increase in resistance after the cycle of R _sei and R _ct was significantly lowered. In other words, it can be seen that the rate of increase in resistance R _sei and R _ct is effectively suppressed by simultaneous doping of these elements.

The present invention is not limited to the above-mentioned embodiments, but can be manufactured in various different forms, and those skilled in the art may recognize other specific forms without changing the technical idea or essential features of the present invention. You will be able to understand that this can be implemented. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

Claims (16)

metal oxide particles including nickel, cobalt, and manganese; and
Five types of doping elements doped into the metal oxide particles
Including,
The five types of doping elements are Al, Nb, B, Zr, and Ti,
The doping amount of Nb is in the range of 0.0005 mole to 0.0025 mole based on 1 mole of the total of nickel, cobalt, manganese and doping elements,
The doping amount of B is in the range of 0.005 mole to 0.01 mole based on 1 mole of the total of nickel, cobalt, manganese and doping elements,
Cathode active material for lithium secondary batteries. delete According to paragraph 1,
The doping amount of Al is 0.006 mole to 0.029 mole based on 1 mole of the total of nickel, cobalt, manganese, and doping elements. delete delete According to paragraph 1,
The positive electrode active material for a lithium secondary battery in which the doping amount of Zr is 0.001 mole to 0.007 mole based on 1 mole of the total of nickel, cobalt, manganese, and doping elements. According to paragraph 1,
The doping amount of Ti is in the range of 0.0002 mole to 0.0015 mole based on 1 mole of the total of nickel, cobalt, manganese, and doping elements. According to paragraph 1,
A positive active material for a lithium secondary battery in which the doping amount of Nb, Al, and Zr satisfies the relationship of Equation 1 below.
[Equation 1]
4 < ([Zr]+[Al])/[Nb] < 210
(In Equation 1, [Nb], [Al], and [Zr] mean the doping amount of each element based on 1 mole of nickel, cobalt, manganese, and the total of the doping elements) According to paragraph 1,
A positive active material for a lithium secondary battery in which the doping amount of Nb, Ti, and B satisfies the relationship of Equation 2 below.
[Equation 2]
3 < ([B]+[Ti])/[Nb] < 120
(In Equation 2, [Nb], [Ti] and [B] mean the doping amount of each element based on 1 mole of nickel, cobalt, manganese and the total of the doping elements) According to paragraph 1,
The positive electrode active material is a positive electrode active material for a lithium secondary battery represented by the following formula (1).
[Formula 1]
Li _a [Ni _x Co _y Mn _z ] _1-t (Al _h Nb _i Zr _j B _k Ti _m ) _t O _{2- p}
(In Formula 1 above,
X is one or more elements selected from the group containing F, N, and P,
a is 0.8 ≤ a ≤ 1.3,
t is 0.008 ≤ t ≤ 0.05,
0.6 ≤ x ≤ 0.95, 0 < y ≤ 0.2, 0 < z ≤ 0.2, 0.006 ≤ h ≤ 0.025, 0.00025 ≤ i ≤ 0.005, 0.001 ≤ j ≤ 0.007, 0.006 ≤ k ≤ 0.029, 0.0002 ≤ m ≤ 0.015, 0 ≤ p ≤ 0.02. According to paragraph 1,
The positive electrode active material for a lithium secondary battery has an initial diffusion coefficient of 6.91*10 ^-9 m ² /sec to 7.58*10 ^-9 m ² /sec. According to paragraph 1,
A positive electrode active material for a lithium secondary battery wherein the crystal grain size of the metal oxide particles is in the range of 1,036 Å to 1,440 Å. According to paragraph 1,
The cathode active material for a lithium secondary battery has a full width at half maximum (FWHM) value for the (110) plane of the metal oxide particle in the range of 0.126 to 0.204. According to paragraph 1,
When measuring the X-ray diffraction pattern, the positive electrode active material for lithium secondary batteries is
I(003)/I(104), which is the ratio of the peak intensity of the (003) plane to the peak intensity of the (104) plane, is a positive electrode active material for a lithium secondary battery in the range of 1.186 to 1.204. According to paragraph 1,
The content of nickel in the metal oxide particles is,
A positive electrode active material for a lithium secondary battery containing 0.8 mol or more, based on a total of 1 mol of the nickel, cobalt, and manganese. A positive electrode comprising the positive electrode active material of any one of claims 1, 3, and 6 to 15;
cathode; and
non-aqueous electrolyte
A lithium secondary battery containing.